Car wont start after head rebuild - BMW Forum

Majin · 09-01-2006, 12:33 AM

I got done rebuilding my head and installed everything like it says in the book. My timing marks are all lined up where they should be but the car will not start. My fireing order is correct, it gets spark to the plugs, and fuel also. can smell it out of the exhaust. I have no blown fuses. could it be the crankshaft position sensor? if not what else could it be?

jfertita · 09-01-2006, 01:44 AM

Did you set your valves to the right things? If you didnt set your valves right its not gonna run.

Majin · 09-01-2006, 02:25 AM

You mean the Valve adjustment? Can the valves cause it not to start from not being adjusted right? The cam is lined up where it should be

DIRTE30 · 09-01-2006, 08:26 AM

There are only four things needed for proper combustion to take place. Fuel, spark, compression, and timing. If all four of these are in proper relation to one another, it will run! Are you sure that your ignition timing isn't 180 out? Just because it has spark doesn't mean it has spark at the right time. Are you sure that you don't have the wires on the dist. cap wrong? Sounds like you do. Double check this by putting each cyl. on TDC and checking to see where the rotor is pointing on the cap and make sure that the wire connected to that post on the cap is going to the correct cyl. Also, have you done a compression check yet? Pretty important to do that after having the head of to make sure that you don't have any leak down. Good luck!

Majin · 09-02-2006, 06:52 AM

I have not done a compression test yet, will be doing that in the next couple days when I get the chance. The compression should be between 142-152psi or 10-11bar? All my timing marks I know are correct from reading about it from muliple places. The cap and wires are numbered so I know they are in the right place. If I dont get the right compression how do I find out why its not getting it.

triggrhaapi · 09-02-2006, 02:35 PM

Quote:

Originally Posted by DIRTE30

There are only four things needed for proper combustion to take place. Fuel, spark, compression, and timing. If all four of these are in proper relation to one another, it will run! Are you sure that your ignition timing isn't 180 out? Just because it has spark doesn't mean it has spark at the right time. Are you sure that you don't have the wires on the dist. cap wrong? Sounds like you do. Double check this by putting each cyl. on TDC and checking to see where the rotor is pointing on the cap and make sure that the wire connected to that post on the cap is going to the correct cyl. Also, have you done a compression check yet? Pretty important to do that after having the head of to make sure that you don't have any leak down. Good luck!

As long as you took off the distributor without removing the wires, you should not have that problem. If you took off the wires, you have a fuckton of work ahead of you. Also double check to make sure your injectors are all wired properly. If your M20 is pre-89 it doesn't have that single harness for the injectors, it has individual wires for each one that are all marked with a number. Also check that all of your sensors are wired properly, your coil is charging properly and your plugs aren't fouled and have the proper gap. Also check your distributor and rotor for burns and corrosion and give them both a good three times over with contact cleaner.

Majin · 09-03-2006, 06:29 AM

I finally got it running. I did a compression check on it. first one was a failure. only about 10psi for each cylinder. Did a valve adjustment then a compression check and everything was fine. It was cause there was no clearance between the valve accentric and the valve itself causing it to not close the valve all the way and lose the compression. Which is what I thought might have been the problem. I Have a few little things to do on it before I get her on the road but thanks for all the advice. I cant wait to take her out for a spin again its been almost 7months.